Circuit breaker



Jan. 7, 1941. M. G. LEONARD 2,227,506

CIRCUIT BREAKER Fild Sept. 10, 1937 4 Sheets-Sheet 1 WlTNESSESi INVENTOR 70, M Merrill 6. Leonard.

Jan. 7, 1941. M. G. LEONARD 2, 6

CIRCUIT BREAKER Filed Sept. 10, 1957 4 Sheets-Sheet 2 WITNESSES: V INVENTOR 4% MZ4, Marni! 6 Leonard. 7% fl/V/QW Jan. 7, 1941. M. G. LEONARD 2,227,506

CIRCUIT BREAKER Filed Sept. 10, 1937 4 Sheets-Sheet 3 7 7 35 5m! $2 9 l mi; 79 n 75 3 M i m 45 25 J 35 ,9 r: lu' Q O qgz fl i M 6 6 7% 3 WITNESSES: INVENTOR Merrill G Leonard.

Jan. 7, 1941. w M. e. LEONARD 2,227,506

CIRCUIT BREAKER Filed Sept. 10, 1937 4 Sheets-Sheet 4 WITNESSES: INVENTOR I Merrz'ZZGLeanard Patented Jan. 7, 1941 UNITED STATES CIRCUIT BREAKER Merrill G. Leonard, Sharon, Pa., assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa., a corporation of Pennsylvania Application September 10, 1937, Serial No. 163,202

19 Claims.

The invention relates to electrical control devices in general, and more particularly, to circuit breakers for mounting in transformers to control moderate power distribution or feeder circuits.

An object of the invention is the provision of an improved circuit breaker which is simple and compact in construction, reliable in operation and which can be manufactured and serviced at a very low cost.

Another object of the invention is the provision of a circuit breaker embodying an improved and simplified operating mechanism which is manually operable to open and close the contacts of the breaker with a snap action and automatically operable to open the contacts with a snap action in response to predetermined conditions irrespective of the position of the operating handle.

Another object of the invention is the provision of a circuit breaker embodying an improved operating mechanism which is mounted in recesses provided in the base of the breaker and the parts of which are held in mounted position by a single overcenter actuating spring which actuates the contacts.

Another object of the invention is the provision of a multi-pole circuit breaker in which the contact means of the several poles are capable of being independently tripped without opening thecontacts of the other poles, but which are simultaneously opened and closed by a common operating member, the common operating member being operable to reset the operating mechanism of any or all poles that have been tripped.

Another object of the invention is the provision of a circuit breaker of the above-mentioned type, any of the poles of which is readily convertible into'a signal-controlling relay to indicate the existence of an abnormal condition.

The novel features that are considered characteristic of the invention are set forth in detail in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will best be understood from the following detailed description thereof when read in connection with the accompanying drawings, in which:

Figure 1 is a plan view partly in section, of the circuit breaker embodying the features of the invention;

Fig. 2 is a sectional view of the circuit breaker taken substantially on the line lI-II of Fig. 1

and looking in the direction of the arrows, the

parts of the breaker being shown in closed circuit position;

Fig. 3 is a sectional view similar to Fig. 2 showing the position of the parts when the breaker is manually opened;

Fig. 4 is a sectional view similar to Fig. 2 showing the position of the parts of the breaker in the tripped open position following a tripping operation;

Fig. 5 is an end elevational view of the circuit breaker illustrating the two current-responsive trip elements, the cover being removed to show these elements;

Fig. 6 is a side elevationalview of one of the current-responsive trip elements of the breaker;

Fig. '7 is a view of the current-responsive trip element shown in Fig. 6 taken at right angles thereto; and

Fig. 8 is a sectional view of the circuit breaker, similar to Fig. 4, showing one of the poles modified to function as an overload responsive signal controlling device.

Referring to the drawings, the circuit breaker illustrated is of the two-pole type and includes a suitably recessed base or casing 9 which is preferably of molded insulating material, and

which serves to support and enclose the various parts of the circuit breaker.. The two poles of the circuit breaker" are substantially identical and hence a detailed description of only one pole The stationary contact I l is secured to the inner angularly bent end of a terminal conducting strip 2| which is secured to an end wall of the casing by suitable rivet fastening means 23. The opposite end of the terminal conducting strip 2| is angularly bent and extends outside of the casing 9 to form a' means for connecting the breaker in an external circuit.

. The movable contact I3 is carried by the switch arm ,l5 which is U-shaped, as best shown I in Fig. 1. The switch arm I5 is stamped from movable contact is secured to a projection 23 which is formed integral with one of the legs of the switch arm and bent at right angles thereto. The bight portion 21 of the switch arm is provided with an angularly bent extension 3| which has a pair of lugs 33 extending laterally from the sides thereof and formed integral therewith, the purpose of which will be hereinafter described.

The actuating means for the movable contact 93 comprises, in general, a pivoted support 35 for the switch arm I5, a movable operating handle 31 and an overcenter spring 39 connecting the operating handle and the bight portion of the switch arm I5.

The pivoted support 35 is stamped from sheet metal plate and formed to provide a pair of spaced parallel legs 4| which are bent angularly as indicated at 43 and joined by a bridge portion 45. The support member 35 is pivotally supported by means of a pivot pin 41, the ends of which are removably seated in suitable bearing recesses 39 formed in the casing. The support member 35 is also provided with a pair of inwardly bent projections 5| which serve as bearings for pivotally supporting the switch arm I5. The switch arm I5 is'nested within the legs II of the support 35 and the upper ends of the legs 25 of the switch arm,

are notched as indicated at 53 for pivotally engaging the bearing projections 5| of the pivoted support 35. It will thus be seen that the switch arm 55 is removably mounted in pivotal engagement with the bearing projections 5| of the pivoted support 35 and that the pivot support is likewise removably mounted in pivotal engagement with the bearing recesses 49 provided in the casing 3, and these elements are adapted to be releasably retained in pivotally mounted position by means of the overcenter spring 39. When in mounted position the switch arm I5 and support 35 form. an articulated switch member.

The operating handle is likewise stamped from sheet metal plates and formed to provide a pair of outstanding parallel legs 55 which are perforated, as indicated at 51, to engage and receive a common operated member which will hereinafter be described. fie operating handle 31 is provided at each end with a pair of lateral projections 59 which are adapted to slide on spaced parallel arcuate surfaces 5| formed on the moulded casing. Suitable ribs 52 are provided on the casing adjacent the arcuate surfaces SI for guiding the operating handle 31 and for preventing lateral displacement thereof. The handle 31 and the bight portion of the switch arm I5 are perforated to receive the bent ends of the overcenter spring 33.

The overcenter spring 39 is held in tension between the bight portion 21 of the switch arm I5 and the operating handle 31 and thus serves to maintain the switch arm I5, the pivoted support 35 and the operating handle 31, in mounted position in the moulded casing, as shown in Fig. 2.

The spring 39 is disposed between the legs of the switch arm i5 and the pivoted support 35, and in the closed circuit position of the switch the line of action of the spring 39 is so disposed relative to the pivot axis 41 of the support 35 that it tends to bias the support in a clockwise direction about its axis ll. The pivoted support 35 is normally held in the position shown in Fig. 2 by means of the current-responsive trip device, the bridging portion 25 of the support 35 being provided with a latch projection 63 which normally engages a latch 65 carried by the trip device, as shown in Fig. 2.

The downward movement of the operating handles 31 is limited by a pair of stops 33 (only one being shown) formed on the arcuate surfaces 6| which engage the upper lateral projections 53 of the handles 31 in the closed circuit positions of the handles shown in Fig. 2, the upward movement of the operating handles being limited by the engagement of the lower lateral projections 59 of the handles with a pair of extending portions 61 formed on the legs ll of the pivoted supports 35 which extend between the sides of the handles 31 and the spaced arcuate surfaces II.

The extensions 81 of the pivoted support 35 and the lower lateral projections 53 of\ the handle 31 form a means for resetting the sdpport 35 when the handle is manually move'd upward beyond its normal open position following a tripping operation, as will be hereinafter described.

The trip device indicated generally at I! comprises a U-shaped bimetallic trip element 33 which has its a bight portion 1| secured to a pivoted adjusting member 13 by means of a plurality of rivets 15. The lower ends of the legs of the bimetallic trip element 33 have an insulating block 11 secured thereto by means of rivets 13. The latch 55, which is angularly off-set, as shown in Fig.2, is secured to the lower end of the block 11 by means of a rivet 3|. Instead oi. a U-shaped bimetal as shown, a single leg bimetal may be used. The pivoted adjusting member 13 is pro-.

vided with a pair of cars 33 which are formed integral therewith and bent at right angles to the portion of the member 13 to which is secured the bimetallic trip element 53. The cars 33 are provided with openings for engaging a pivot pin 35 which is mounted in the casing 3. The adjusting member 13 is thus pivotally moimted in the casing and it will be seen that a small rotative movement of the pivoted adjusting member 13 about its pivot pin 35 will change the position of the latch 55 with respect to the latch projection 33 provided on the pivoted support 35.

The adjusting member 13 is provided with an angularly off-set extension 31 by means of which the member 13 may be moved to adjusted position about its pivot axis 33.

The right-hand end of the extension 31 of the adjusting member 13 is notched to receive an adjusting screw 33 which passes through a transverse wall 3| formed in the casing '3. The screw 83 is held in mounted position on the transverse wall 9| by means of a nut 33. An internally A coil spring I03 encircles the bolt 33 and en-' gages the notched end of the extension 31 of the adjusting member 13 at one end and the transverse wall 8| at its other end The spring I33 serves to maintain the extension 31 of the adjusting arm 13 in engagement with the adjusting screw 95, as is shown in'Flgs. 2, 3 and 4. The front wall 93 of the casing 3 is provided with a semi-circular rib I31 which increases the creelage breakdown strength between the two poles and which may serve as an index scale for the indicating pointer I III. rib I01 is provided with an inward projection III! which serves to limit rotation of the pointer IOI and adjusting screw 35 in either direction.

From the above description of the trip device,

The mid-portion of the it will be apparent that when the screw is turned in a clockwise direction, as viewed in Fig. 1, it will move the adjusting member 13 in a clockwise direction about its pivot pin 85, as viewed in Figs. 2, 3 and 4, and the clockwise movement of this adjusting member 13 will decrease the amount of overlap between the latch 55 carried by the trip element 59 and the latch projection 63 formed on the pivoted support 35. This adjustment of the screw 95 and resulting decrease in the overlapping engagement between the latch 65 and the latch projection 53 will cause the breaker to be tripped in response to a lower magnitude overload. Conversely, when the screw 95 is turned in a counter-clockwise direction, as viewed in Fig. l, the amount oi overlap between the latch 65 and the latch projection 53 is increased, so that under these conditions, the breaker will be tripped in response to a higher magnitude overload.

As has been previously mentioned, the structures" of the two poles of the circuit breaker are identical, and are insulated from one another by a centrally disposed partition Ill formed in the casing 9. The operating handles 31 of the two poles are connected ior simultaneous movement together by a common operating member I, of insulating material, the operating member lil being connected to the two poles by means of a yoke H3, the opposite arms 5 of which extend through the openings 51 provided therefor in the operating handles 31..

A suitable cover H1 of molded insulating material is provided for enclosing and protecting the current responsive trip devices is. The cover H1 is provided with a central partition H3 which aligns with the partition ill formed in the casing 9 so as to completely isolate the two poles of the breaker from one another.

The circuit for each pole ofthe breaker is the same and extends from a terminal strip III, the end of which extends outside of the casing, through a flexible shunt conductor I23 to one leg of the bimetallic trip element 83 through the trip element 69, and a flexible shunt conductor I25 to the switch arm l5, through the switch arm l5 to the movable contact i3 and stationary contact I I to the terminal strip 2 l The operation of the circuit breaker is briefly as follows: Withthe circuit breaker in closed position, as shown in Fig. 2, let it be assumed that it is desired to manually open the contacts of the breaker. To manually open the breaker, the common operating member III is moved in an upward direction, as viewed in Fig. 2 to eflect simultaneous upward movement oi! the two operating handles 31. The upward movement oi. the operating handles 31 moves the line of action of the over-center springs 33 across and above the pivot axes 53 of the switch arms l5. As soon as the line of action of the over-center Springs crosses above the pivot axes 53, a component of the force exerted by the springs moves the two switch arms from closed position, as shown in Fig. 2, to the open circuit position shown in Fig. 3. This movement of the switch arms takes place with a snap action. The movement of the. switch arms to open circuit position is limited by the engagement of the projection 3| oi the switch arms II with the transverse walls 9| formed in the casing, as shown in Fig. 3.

To manually close the circuit breaker, the common operating member III is moved downwardly as viewed in Fig. 3, to effect simultaneous downward movement of the two operating handles 31.

The downward movement of the operating handles 31 moves the line of action of the overcenter springs 33 across and below the pivot axes 53 of the switch arms l5. As soon as the line of action of the over-center springs 39 crosses the pivot axes 53 of the switch arms I5, 9. component of the force exerted by the springs moves the switch arms l5 from open circuit position shown in Fig. 3 to the closed circuit position shown in Fig. 2 with a snap action. As has been previously mentioned, the downward movement oi the operating handle is limited by the engagement of the lateral projections 53 of the handles with stop projections formed on the spaced arcuate guide surfaces 5|. It will thus be seen that predetermined movements of the common operating member lli eflect simultaneous opening and closing of the contacts of the two poles of the circuit breaker; the contacts of the two poles are capable of being independently tripped, however, by the trip devices.

When an overload of predetermined magnitude and duration occurs in the circuit through either one of the poles of the circuit breaker, the breaker being in closed position as shown in Fig. 2, the bimetallic trip element 59 of that pole is heated a suflicient amount to deflect in a direction away from the actuating means. The deflection of the trip element 59 causes the latch 55 to disengage the latch projection 63 of the pivoted support member 35, thus releasing the support member. When the support member 35 is released the overcenter spring 39 of the actuating means of that pole moves the pivoted support 35 in a clockwise direction about its pivot axis 41 from the position shown in Fig. 2 to the position shown in Fig. 4. During this movement, the legs ll of the pivoted support 35 engage the lateral projections 33 of the switch member l5 and move that member to a tripped open position, as shown in Fig. 4, with a snap action to efiect opening of the contact means and interruption of the circuit. Due to the fact that the contact means 01' the two poles have individual trip-free actuating means, the tripping open of the contacts of one pole of the breaker does not affect or change the position of the contacts of. the other pole so that the contacts of the other or unaflected pole remain in closed position. When both poles are tripped, however, as described above in connection with one pole, the connected operating handles 31 and of course the common operating member III are moved to an intermediate trip indicating position by the over-center springs 39 providing this movement is not restrained by the operating mechanism, the movement of the handles 31 to their intermediate trip position being limited by the engagement of the lower lateral projections 53 of the handles 31 with the extensions 51 of the movable supports 35. Y

Before the contact means can be reclosed following a tripping operation in either pole, it is necessary to reset the pivoted support 35 or the tripped pole to its normally latched position. To reset the circuit breaker following a tripping operation, the common operating member III is moved in an upward direction beyond the normal open'circuit position thereof. During this movement, the lower lateral projections 55 of the handle of the tripped pole which engage the extensions 51 of the pivoted support 35 move that support in a counter-clockwise direction about its pivot axis 41 to return the support to its normally 7 tion the common operating member III must be moved upward beyond normal or manual open circuit position. After the pivoted support 35 has been returned to latched position, the breaker may be manually reclosed in the manner previously described.

The structure of the circuit breaker is such that either of the poles thereof, or both of them, may be readily converted into a current-responsive signal controlling device. The manner in which either pole of the circuit breaker may be converted into a signal controlling device is illustrated in Fig. 8 of the drawings. The shunt conductor I instead of being connected to the switch arm 15, is connected directly to the outgoing terminal strip 2!. The switch arm I5 is provided with an auxiliary contact iIB which is secured to the angular projection SI of the switch arm. A cooperating stationary contact I I8 is securedto the transverse wall Si in a position to be engaged by the auxiliary movable contact IIS when the switch arm is moved by the actuating means to the tripped open position, as shown in Fig. 8. If desired, the contact I18 may be made longer so that it will be engaged by the contact H6 in both the tripped and manual open position of the switch arm l5.

The circuit through the converted pole of the breaker extends directly through the corresponding current-responsive trip element 69, and the main contacts ii and 13 are not used. Thus the converted pole of the breaker does not function to interrupt the main circuit through such pole. The other pole, however, if unconverted, functions as a circuit breaker. The auxiliary contacts IIS and H8 may be connected in a suitable signal circuit which is adapted to be energized by the closure of these'contacts when the switch arm i5 of the converted pole is tripped. The bimetallic trip element 6 9 of the signal controlling pole may be adjusted by means of the screw 95 to trip the switch arm open at any desired predetermined overload. The signal circuit controlled by the contacts Hi and II 8 may receive electrical energy from the line and transformer to which the breaker is connected by providing a shunt conductor I26 for connecting the terminal strip 2| with the switch arm I5.

It will thus be seen that the invention provides an improved circuit breaker which is simple and compact in construction, reliable in operation and which can bemanufactured and serviced at a very low cost. The particular structure of the circuit breaker whereby the handles, switch arms and the pivoted supports are removably mounted in the molded casing and releasably held in mounted position by means of the over-center spring which actuates the switch arms, provides a very desirable and inexpensive circuit breaker structure. It will be noted that there is but a single hearing means for the actuating mechanism which consists of the bearing recesses 49 formed in the molded casing. This bearing means and the arcuate guide surfaces SI for the operating handles together with the feature of the over-center springs acting to hold the various parts of the actuating means in mounted position entirely eliminates the necessity of a. separate frame for supporting the actuating means and thus materially reduces the manufacturing cost of the circuit breaker. The structure of the actuating mechanism is such that the contacts of the breaker are opened and closed with a snap action and the actuating mechanism of either pole that is tripped may be readily reset by simply moving the common operating member to a position beyond the normal manual open position.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes may be made in the structural details thereof without departing from the spirit of the invention. It is desired, therefore, that the appended claims be given the broadest reasonable construction in the light of the prior art.

I claim as my invention:

1. In a circuit breaker, a switch member movable to open and to closed circuit position, actuating means therefor comprising a movable opcrating member and an overcenter spring for moving said switch member to open and to closed circuit position, a pivoted member releasable to cause automatic opening of said switch member independently of said operating member, and a pivoted bimetal trip element normally restraining said releasable member, a casing of molded insulating material for the breaker having a molded guide surface for said operating member which constitutes the sole support for said oper ating member and along which said operating member is movable, said casing having bearings molded therein for said pivoted releasable member and for said pivoted bimetal element.

2. In a circuit breaker, a switch member'movable to open and to closed circuit position, actuating means therefor comprising a manually operable operating member and an overcenter spring connected to said operating member, for

moving the switch member alternately to open and to closed circuit position, and a pivoted trip member movable to cause automatic opening of said switch member independently'of said manual operating member but remaining stationary during normal movement of said operating member, a casing of molded insulating material for said breaker, said casing having a molded pivot bearing for said trip member which directly engages and supports the pivot of said trip member and having a molded bearing for said manually operable operating member which directly engages and constitutes the sole support for said Operating member, said overcenter spring serving to maintain said operating member in mounted engagement with its molded bearing.

3. In a circuit breaker, a. pivoted support, trip means releasably retaining the support in operative position, a switch member pivoted to said support and movable to open and to closed circuit position, a movable operating member, an

overcenter spring connecting said operating member to said switch member for moving the switch member to open and to closed circuit positions in response to predetermined movements 01 said operating member and for moving said support to an inoperative position when released to cause movement of the switch member to open circuit position, a casing provided with a bearing means for pivotally supporting the movable support, and also provided with an armate guide surface along which said operating member is movable and which constitutes the sole support for the operating member, said guide surface having a slot for accommodating the connection or said spring in said handle.

4. In a circuit breaker, a pivoted support, trip means releasably retaining the support in operative position, a switch member pivoted to said support and movable to open and to closed circuit position, a movable operating member, an overcenter spring connecting said operating member to said switch member for moving the switch member to open and to closed circuit position in response to predetermined movements of said operating member and for moving said support to an inoperative position when released to cause movement of the switch member to open circuit position, a casing provided with a bearing means in which the pivoted support is removably pivoted, and also provided with spaced arcuate guide surfaces disposed in the same arcuate plane along which said operating member is movable, said guide surfaces constituting the sole support for the operating member, said spring being connected to said operating member through the space between the guide surfaces and serving to yieldingly maintain said support in engagement with the bearing means and the operating member in engagement with the guide surfaces.

5. ,In a circuit breaker, relatively movable contacts, actuated means therefor including a normalLy restrained biased member releasable in response to predetermined conditions to cause opening of said contacts, and an operating member movable to open and to closed position to cause said actuating means to open and to close said contacts, a casing for'said contacts and actuating means provided with an elongated opening bounded on its two long sides by a pair of spaced parallel arcuate guide surfaces for supporting said operating member and along which said operating member is movable, said operating member having lateral projections for slidably engaging said guide surfaces, said releasable member having a portion which projects into the path of at least one of said projections between said operating member and one of said guide surfaces when said member is released to be engaged and moved by said projection for resetting said releasable member in response to a predetermined movement of said operating member.

6. In a circuit breaker, a recessed base, a stationary contact mounted on said base, a pivoted support having a removable pivotal engagement with bearing means provided in said base, a contact arm pivoted to said support, trip means for releasably retaining said support in operative position, an operating handle movable along a guide recess provided on the base, and an overcenter spring connecting said handle to said contact arm for moving said arm into and out of engagement with the stationary contact in response to movement of said handle and for moving said support to an inoperative position when the support is released bythe trip means for moving the contact arm to open position, said spring serving 1 to maintain said support in engagement with its bearing means and said handle inengagement with the guide recess, and said guide recess con-. stituting the sole support for said handle.

'7. In a circuit breaker, a base having a recess, a stationary contact mounted in the recess, an articulated switch member having a support portion removably mounted in the recess in pivotal engagement with hearing means provided on the base, and a contact portion movable relative to the support portion, trip means for releasably retaining the support portion of the switch member in operative position, an operating handle movable along a guide surface provided on the base, and an over-center spring connecting the operating handle to the contact portion of the switch member for moving the contact portion to open and to closed position in response to movement of the handle and for moving the support portion to'inoperative position to effect movement of the contact portion toopen position when the support portion is released by the trip means, said spring serving to maintain said switch member and handle in mounted position on the base, and said guide surface constituting the sole support for said handle.

8. In a circuit breaker, a base having a recess, a stationary contact disposed in the recess, a pivoted support removably mounted in pivotal engagement with hearing recesses formed in the side walls of the recess, a contact arm pivotally engaging said support, trip means for releasably retaining the support in operative position, an operating handle movable along a guide surface provided on said base, and an over-center spring connecting the handle to the contact arm for moving the contact arm to open and to closed circuit position in response to predetermined movements of the operating handle and for moving the support when released by the trip means to an inoperative position to effect movement of the contact arm to open position, said spring serving to maintain said support in engagement with its pivot bearing recesses, said handle in engagement with its guide and said contact arm in pivotal engagement with'the support.

9. In a circuit breaker, a base of moldedinsulating material having bearings molded therein, a switch member movable to open and to closed position, actuating means for the switch member including a releasable support for the switch member movable to an inoperative position when released to cause openingmovement of the switch member, means normally holding said support stationary, a movable operating handle and an over-center spring connecting the handle to the switch member for actuating the switch member in response to predetermined movements of the handle and for moving the support to its inoperative position when released, said support remaining stationary during manual operation of the breaker, said support and said handle being removably mounted in engagement with the bearings and held in mounted position by said spring.

10, In a multi-pole circuit breaker, a plurality of poles, each comprising a pivotally mounted tion, a movable operating handle, an over-center spring connecting the handle to the contact member for actuating the contact member in response to predetermined movements of the operating handle and for moving the support to an inoperative position when released by the trip means to cause movement of the contact member from one position to another position irrespective of the position of the operating handle, and a single movable operating member connected to the oper ating handles of the several poles for simultaneously operating all of the switch members.

11. In a multi-pole circuit breaker, a plurality of independently movable switch members one for each pole, a contact on each switch member, an individual actuating means for each switch member comprising a releasable support for the switch member movable from a normal latched position to an inoperative position to cause movement of the switch member from one position to another whereby operation of any one of the trip means causes movement of its corresponding switch member only, without changing the position of the other switch members, a single unitary base of molded insulating material on which the aforementioned parts of the breaker are mounted.

12. In a multi-pole circuit breaker, a plurality of independently movable switch members one for each pole, an individual actuating means for each switch member comprising a pivoted releasable support for the switch member movable from a normal latched position to an inoperative position to cause movement of the switch member from one position to another position, each switch member directly pivotally engaging its releasable support, a movable operating handle, an over-center spring connecting the handle to the switch member for moving the switch member between said positions in response to the movements of the handle and for moving the support to an inoperative position when the same is released, and a trip means operable to effect release of the support in response to predetermined conditions comprising a pivotally mounted bimetal trip element for each support; a common operating member connected to the several operating handles for simultaneously operating the switch members to their two positions, each trip means being operable entirely independently of the other trip means and being free of any connection with the other trip means whereby operation of any one of the trip means causes movement of its corresponding switch member only without changing the position of the other switch members, said operating handles having means for engaging and resetting the supports to their normal latched position in response to a predetermined movement of the operating member, and a single unitary base of molded insulating material on which the aforementioned parts of the circuit breaker are mounted, said base having bearings molded therein for said pivoted releasable supports and for said pivoted bimetal elements. 7

13. In a circuit controlling device, a movable switch member, a support for the switch member that is movable from a normal position to a tripped position for moving said switch member to a tripped position, said switch member being mounted in pivotal engagement with said support, trip means for normally retaining said support in its normal position and operable in response to predetermined conditions to release said support, a movable operating handle, an

over-center spring connecting said handle to said switch member for moving said switch memher in response to predetermined movements of said handle and for moving said support to its tripped position when the same is released, a stationary contact engaged by said switch member only when the switch member is in itstrlpped position.

14. In a circuit controlling device, a movable switch member, a support for the switch member that is movable from a normal position to a tripped position to cause movement of the-switch member to a tripped position, said switch member being mounted in pivotal engagement with said support, trip means for normally restraining said support in its normal position and operable to release the same in response to predetermined conditions, actuating means for moving the switch member independently of the support, and for moving the support from its normal to its tripped position when the support is released, and for resetting said support to its normal position, and a contact disposed to be engaged by said switch member only when the switch member is in its tripped position.

15. In a circuit breaker, a base of molded insulating material having a bearing molded therein of the same material as the base, a support pivoted in said bearing directly on the insulating material of said base, a movable contact arm, trip means for releasably retaining said support in a predetermined position, an operating handle movably supported directly on the insulating material of the base for moving the contact arm to open and to closed circuit position, said support when released by said trip means causing movement of said contact arm to an open circuit position.

16. In a circuit breaker, a base of molded insulating material having a bearing molded therein of the material of the base, a support removably pivoted in said bearing directly on the insulating material of said base, trip means for releasably retaining said support in a predetermined position, a movable contact arm, an operating handle removably supported directly on the insulating material or said base, an overcenter spring for moving said contact arm to open and to closed circuit position in response to movement of said handle to open and to closed position, and for moving said support when released by said trip means to cause movement of said contact arm to an open circuit position.

17. In a circuit breaker, a base of molded insulating material having a bearing molded therein of the material of the base, a pivoted support removably mounted in pivotal engagement with said bearing directly on the insulating material of said base, a contact arm pivoted to the support, trip means for releasably restraining said support in operative position, an operating handle movable along a guide surface on said base or the material of the base, an overcenter spring connecting said handle to said contact arm for moving said arm to open and'to closed circuit position in response to predetermined movement of said handle and for moving said support to a tripped position when the support is released by the trip means to cause movement of the contact arm to an open circuit position, said spring maintaining said support in engagement with its bearing and said handle in engagement with said guide surface. 18. In a circuit breaker, a casing of molded insulating material, relatively movable contact means in said casing, actuating means for said contact meam comprising a movable operating handle and an overcenter spring connected to said handle for manually actuating said contact means, and a pivoted member releasable in response to predetermined conditions to cause automatic opening of said contact means irrespective of the position of said handle, said releasable support normally being held stationary and remaining stationary during manual operation or the breaker, said casing having a molded bearing surface for said operating handle which directly engages and constitutes the sole support for said handle and having a molded pivot bearing which directly engages and supports the pivot of said releasable member.

19. In a circuit breaker, a casing of molded insulating material molded to provide a chamber, a stationary contact in said casing, an arcuate bearing groove at one end of said casing having a central elongated opening therein joining said chamber, a pair of blind recesses in the sides of said casing extending inwardly from the opposite end of said casing along the sides 01' said chamber toward the arcuate bearing groove, the blind ends of said recesses forming bearings, a stationary contact mounted in said chamber, a yoke shaped carrier lever pivoted on a pivot pin supported in the bearings formed by said blind recesses, a.yoke shaped contact carrying member disposed between the sides of said carrier lever and pivoted to said carrier lever, a contact on said contact carrying member for engaging said stationary contac an operating handle bearing against said arcuate bearing surface and movable back and forth along said surface, an overcenter spring connecting said contact carrying member and said operating handle, said spring being disposed between the sides of said contact carrying member and having a connection with said handle through said elongated opening in said arcuate guide surface, and a thermally controlled latch for normally engaging and restraining said carrier in an operative position.

MERRRL G. LEONARD. 

